One of the freedoms we Americans hold dear is freedom of choice we want to be free to choose where we live, our type of transportation, what we wear (or don't), who our leaders are, and what we eat and drink. And in most cases, we really do have a lot of choice. Nowhere is this more true than with respect to food. It would be nice, however, if we could make reasonable, informed choices about our diets. Since most of us aren't nutrition experts, we rely on those who are to help us make at least some of those choices, at least some of the time.
Lately, however, such reliance has been more difficult than usual.
First, there was the long article in the July 7 Sunday New York Times magazine questioning whether a low-fat diet is really good for us. Would it perhaps be better for heart, girth, and overall health to follow the much-maligned but slowly-gaining-acceptance Atkins high-fat, eat-all-the-butter-you-can, ketogenic diet?
Just a day later, Time magazine published a long article on the pros and cons of going vegetarian if, of course, you can figure out exactly what a vegetarian is (there are several levels of severity).
And then, but one day after that, noted anthropologist Lionel Tiger chimed in with an opinion piece in the Wall Street Journal. He offered us historical (rather than hysterical) reasons to follow a diet based on meat and such like the ones our cavemen forbears supposedly enjoyed (when they could catch it, that is).
So, here we are, being bounced back and forth like ping pong balls, with factions on all sides claiming that whatever evidence there is supports their views. The idea seems to be that if we only ate a preponderance of our calories from _______ (fill in your favorite macronutrient: fat, carbs, or protein) we would stem the tide of obesity that threatens to engulf us, diminish the incidence of heart disease, and perhaps promote world peace.
It's all well and good to picket for one's favorite food, but there does seem to be one item missing from most popular discussions of dietary advice, including the three mentioned above. That item is the importance of energy balance that is, calories in (as food) versus calories out (as physical activity, including exercise). Maybe because it's hard to measure accurately in a population with widely divergent lifestyles, energy balance often seems to be left out of most popular discussions of nutrition and weight loss advice.
Yet, unless and until the laws of thermodynamics are repealed (for example, energy can neither be created nor destroyed) the most important determinant of an adult's body mass is his or her energy balance. But in spite of this relationship, we seem to get hung up over and over again on the form our calories take, rather than the sheer bulk of them.
While it certainly may be true that some populations who consume a relatively high proportion of their calories from fat (e.g., some folks in the Mediterranean region) have less heart disease than we do, it's also true that other populations with less heart disease eat less fat than we do. So it can't be just the fat, and it can't be just the diet, in my opinion.
We don't eat like cavemen, as Lionel Tiger urges, but we're not active like cavemen, either. The activity trends in this country seem to have been pointing down for the last several decades. And that's not just because of more TVs and computer games, though certainly these play a role. All sorts of subtle changes in society contribute to our diminishing exertion. Those of us over a certain age can even recall when driving a car took more physical energy than it does today. Remember trying to parallel park a car without power steering? Or having to actually move the seat manually without a power-assist?
Small differences add up but are hard to track. Before we bounce again between the high carb and high fat factions and waste a lot of time and energy arguing which is the best diet, let's stop and think a bit about our high energy in/low energy out lifestyles. It ain't a pretty picture, but it's a good predictor of what size we'll end up being. And eating like a caveman won't necessarily change that.